VERNON, Vt. — A state license for the Vermont Yankee nuclear plant to operate for another year until its permanent shutdown might seem of little importance, but the Connecticut River Watershed Council is urging Vermont’s Public Service Board to include language influencing the release of heated water from the 41-year-old reactor.

The state board, which is weighing terms of a Certificate of Public Good setting conditions for the Vernon plant, is being asked by the Greenfield-based conservation organization to require the plant to return to “closed-cycle” cooling for its process water rather than continuing to discharge heated water into the river.

“We see this as an important decision generally, as well as specifically,” said Watershed Council Executive Director Andrew Fisk, adding that it can have ramifications around the country, for all kinds of power plants and how they’re required to deal with effluent.

Vermont Yankee, which operated for about 18 years without discharging heated water into the river, under a “closed cycle” system before beginning to discharge warm, non-radioactive water, has an expired water discharge permit issued a dozen years ago by the state’s Agency of Natural Resources.

Fisk acknowledged, “Obviously, the plant is going to close in a year, and the thermal pollution will go away then.”

But the organization, which he explained, “has been having this conversation in Vermont at multiple levels for more than a decade,” also hopes to influence how energy-generating plants of all kinds demonstrate whether by discharging their cooling water into rivers, they’re heating ambient water temperatures enough to harm fish and other aquatic life.

“The state, frankly, has not required enough, or the right, information, and has not constructed a permit sufficient to safeguard the river,” he said. The watershed council says there is no sufficient argument to continue “thermal pollution,” so the state’s permit should require closed-cycle cooling, with use of cooling towers all the time.

Instead, Vermont Yankee’s state discharge permit, issued 12 years ago by the state Agency of Natural Resources, sets specific limits for how much water can be discharged in summer and winter, depending on water temperature.

The U.S. Environmental Protection Agency, which generally enforces thermal water pollution under authority of the Clean Water Act, is updating its rules for how cooling water is released, and Fisk says that considering studies that the watershed council has presented to the Public Service Board, the state could show other states around the region the kinds of scenarios that should be factored into their decision-making as well.

“There are no formal regulations yet from EPA on requiring closed-cycle cooling,” he said. “That’s why we think this conversation is very important. It’s more than just a facility on the Connecticut River in Vernon, Vt.”

David Deen, the council’s Vermont river steward, added that with at least two more migratory periods for American shad and other anadromous fish, the potential removal of the heated-water “barrier” for those species is worth the effort of pressing ahead with arguments that have been made during 18 months of state licensing.

“When other utility boards around the country look for precedents in terms of controlling thermal discharge, getting a decision we’re happy with out of the board could have some value down the road for other situations into the future.”

Although the state’s natural resource agency hasn’t issued a new discharge permit for the plant, which therefore continues operating under the existing one, the Public Service Board may consider water quality under its statute for issuing the license the state mandates.

The natural resources agency, in an Oct. 25 filing with the public service board, writes that Entergy “persisted in relying principally on its (discharge) permit in this proceeding, despite the substance and volume of testimony demonstrating the inadequacy of that evidence.” The agency says the plant’s data is more than 10 years old.

Deen, who testified as an expert witness before the board last April, quoted a report that questions the way the water’s temperature increase is calculated and questioned the list of fish species considered by the plant’s owners as part of its study on effects of the discharge.

“We’ve said this 12-year-old permit is based on a performance equation that was first devised in 1978, and we have a report that says that report ain’t worth squat. It doesn’t predict what the water temperatures are going to be.”